If it’s too tall for your taste now it is the wrong tree for that position. If it’s just the long whippy growth you object to don't worry. That’s normal and it will sort itself out. Cutting the top off will just cause twiggy branching and it will end up misshapen and spreading onto the path.

I topped the leader on my pear tree when it was around 5 years old, I think, and it didn't cause any problems. My pear tree tends to grow very upright -- it's Nova, iirc.

Is there any harm of pear tree to be close to sidewalk?

You're going to have pears fall on the sidewalk and make a mess. That's if any pears ever get near to being ripe before you get takers on the pears you "offered" to the public.

I would tie down some of those tall branches so that they grow semi horizontal.

The natural habit/form of a fruiting pear, Pyrus communis, is very upright and narrow, much like the ornamental pear, Pyrus calleryana. It wants to grow tall, unless on a dwarfing rootstock. I'd do some research on how to prune these as fruiting trees often require specialized pruning techniques to maximize fruit production. YouTube is one place to start (not the best but mostly functional) but I would certainly look into fruit tree pruning classes typically offered by many retail nurseries in late winter and early spring. You want to learn how to encourage the fruiting spurs or growth points along at least 2 and 3 year old growth, as this is how and where pears produce fruit.

And no, there is no harm to the tree being planted that close to the sidewalk, although dropping and/or stolen fruit could b an issue.

Here is one website that provides a rough summary: https://www.starkbros.com/growing-guide/how-to-grow/fruit-trees/pear-trees/pruning

The harm would come from the tree roots eventually damaging the sidewalk as they try to surface (the cement will impair passage of air and water to the roots, so they try to get to the surface- even when they have clear space around the rest of the tree.) It is a common problem. The only exception might be if it is on a very dwarfing rootstock, which doesn't have extensive roots.

I have a standard pear that I keep pruned to keep shorter - It is a twice/year chore, but not difficult.

We don't know whether this is a fruiting or ornamental pear but either way there is a problem if it is too close to the sidewalk. As a pedestrian, being slapped in the face by overhanging branches is no fun, especially when they're wet.